Adelbert von Chamisso
Adolf Engler
Adolfo Lutz
Adolphe Theodore Brongniart
Agnes Robertson Arber
Agustín Stahl
Aimé Bonpland
Albert Francis Blakeslee
Albert Günther
Albert Howard
Albert von Kölliker
Albert William Herre
Alcide d'Orbigny
Aleksandr Fyodorovich Middendorf
Aleksandr Oparin
Alexander Agassiz
Alexander G. von Bunge
Alexandre de Cassini
Alfred Brehm
Alfred Cogniaux
Alfred Grandidier
Alfred Merle Norman
Alfred Newton
Alfred Romer
Alfred William Alcock
Alister Clavering Hardy
Allan Octavian Hume
Alpheus Hyatt
Amy Castle
André Lwoff
André Marie Constant Duméril
André Michaux
Andrea Cesalpino
Andrew Jackson Grayson
Ángel Cabrera
Antoine de Jussieu
Antoine Laurent de Jussieu
Anton de Bary
Anton Dohrn
Antoni van Leeuwenhoek
Antonina Georgievna Borissova
Archibald Vivian Hill
Aristid Lindenmayer
Armand David
Asa Gray
August Johann Georg Karl Batsch
Augustin Pyramus de Candolle
Augustus Addison Gould